The present disclosure generally relates to railroad right-of-way maintenance machinery, and more particularly relates to machinery used for driving fasteners into rail ties for securing rail tie plates and rails to the ties.
Rail fasteners as contemplated herein include cut spikes, lag screws, hairpin spikes and other types of rail fasteners used for retaining tie plates upon ties, and rails upon tie plates, as are known to skilled practitioners. In some cases in the specification, “spikes” may be used interchangeably with “rail fasteners.” The use of the term “spikes” is not intended to limit the scope of the present invention.
During the course of railroad maintenance work, it is common that existing rail fasteners are removed for replacement of rail ties, tie plates, rails and for other maintenance operations. Once the desired maintenance is complete, the fasteners need to be reinstalled. For installing the fasteners, a conventional spike driving workhead unit employs an elongated shaft-like anvil which is vertically reciprocating relative to a spotting carriage to drive the fasteners into the ties. Under the upward and downward actions of a hydraulic impact hammer, the anvil repeatedly applies downward pressure upon spikes in a pushing or percussion function. After extended use, a spike engagement end of the anvil wears out and thus it needs to be replaced. To perform maintenance on the conventional spike driving workhead unit, a hole must be dug in the ballast so that conventional guide rods can be lowered below a hammer bushing, which is very inconvenient for replacement of the worn-out anvil.
Further, because the conventional guide rods are fastened with transverse threaded fasteners such as bolts, vibrations and impacts caused by the percussive actions of the hammer loosen and eventually shear the bolts. Spring pins are also used to fasten the guide rods to the jaw block, but as with the bolts the spring pins also fail due to the same reasons stated above. Failures of other moving components are also caused by manufacturing tolerances, thereby creating loose connections and improper alignments when assembled. Therefore, there is a need for securing a decreased chance of component failure and increasing serviceability of the conventional spike driving workhead unit during maintenance.